&nbsp389 &nbspFXUS10 KWNH 141846 &nbspPMDHMD &nbsp &nbspMODEL DIAGNOSTIC DISCUSSION &nbspNWS WEATHER PREDICTION CENTER COLLEGE PARK MD &nbsp143 PM EST WED FEB 14 2018 &nbsp &nbspVALID FEB 14/1200 UTC THRU FEB 18/0000 UTC &nbsp &nbsp...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR &nbspINGEST... &nbsp&nbsp &nbsp..12Z MODEL EVALUATION WITH LATEST MODEL PREFERENCES/CONFIDENCE &nbsp &nbsp~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ &nbsp&nbsp &nbsp..CLOSED LOW INITIALLY OFFSHORE SOUTHERN CALIFORNIA &nbsp &nbsp~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ &nbspPREFERENCE: GENERAL MODEL BLEND &nbspCONFIDENCE: ABOVE AVERAGE &nbsp &nbspTHE MODELS TAKE THE UPPER LOW OFFSHORE SOUTHERN CALIFORNIA &nbspGRADUALLY OFF TO THE EAST AND INLAND ACROSS THE DESERT SOUTHWEST &nbspOVER THE NEXT 12 TO 24 HOURS. AS THE ENERGY MOVES INLAND, IT WILL &nbspBE DEAMPLIFYING, AND IT IS EXPECTED TO SHEAR OUT ACROSS THE FOUR &nbspCORNERS REGION ON THURSDAY. THE LATEST GUIDANCE IS IN GOOD &nbspAGREEMENT ON THE DETAILS OF THIS, AND SO A GENERAL MODEL BLEND &nbspWILL BE PREFERRED AT THIS TIME. &nbsp &nbsp&nbsp &nbsp..SHORTWAVE DIGGING DOWN ACROSS THE PACIFIC NORTHWEST TODAY &nbsp&nbsp &nbsp..ENERGY DIGGING INTO THE SOUTHWEST BY THURSDAY &nbsp&nbsp &nbsp..EJECTING RAPIDLY EAST ACROSS THE SOUTHERN U.S FRIDAY. &nbsp&nbsp &nbsp..SOUTHERN STREAM SHORTWAVE OVER TENNESSEE VALLEY BY SATURDAY &nbsp &nbsp~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ &nbspPREFERENCE: BLEND OF THE 12Z GFS/12Z UKMET AND 12Z ECMWF &nbspCONFIDENCE: SLIGHTLY ABOVE AVERAGE &nbsp &nbspTHE MODELS ALLOW SHORTWAVE ENERGY CURRENTLY DIGGING SOUTH DOWN &nbspACROSS THE PACIFIC NORTHWEST TO DROP DOWN INTO THE SOUTHWEST U.S. &nbspBY THURSDAY WHICH WILL EFFECTIVELY HELP KICK THE CURRENT ENERGY &nbspOVER THE SOUTHWEST DOWNSTREAM IN A SHEARED FASHION. THE NEW &nbspSHORTWAVE FOCUSING OVER THE SOUTHWEST WILL THEN TEND TO CAPTURE &nbspSOME OF THE SHORTWAVE/VORT ENERGY IN THE SUBTROPICAL STREAM TO THE &nbspWEST OF THE BAJA PENINSULA AND THEN BEGIN RAPIDLY EJECT DOWNSTREAM &nbspACROSS THE SOUTHERN U.S. BY FRIDAY. A SOUTHERN STREAM SHORTWAVE &nbspREMNANT WILL THEN QUICKLY ARRIVE ACROSS THE LOWER MISSISSIPPI &nbspVALLEY AND TENNESSEE VALLEY REGION BY SATURDAY WHILE ATTEMPTING TO &nbspALSO DEVELOP A WEAK SURFACE LOW. THE 12Z NAM IS MORE SHEARED AND A &nbspBIT WEAKER WITH THE SOUTHERN STREAM ENERGY AND TENDS TO PLACE MORE &nbspEMPHASIS ON NORTHERN STREAM ENERGY INSTEAD ACROSS THE MIDWEST. THE &nbsp12Z GFS, 12Z ECMWF AND 12Z UKMET ARE BETTER DEFINED AND SUPPORT A &nbspPROGRESSIVE SYSTEM, BUT THE UKMET MAY BE A TAD TOO STRONG WITH ITS &nbspSURFACE LOW DEVELOPMENT AT THE END OF THE PERIOD OVER THE &nbspTENNESSEE VALLEY. THE UKMET ALSO IS SHOWING A BIT MORE &nbspNORTHERN/SOUTHERN STREAM INTERACTION BY SATURDAY UPSTREAM OVER THE &nbspTHE MIDWEST WHICH THE ECMWF IS SHOWING AS WELL, BUT WITH THE UKMET &nbspA BIT SLOWER. BASED ON THE LATEST ENSEMBLE MEANS FROM THE GEFS AND &nbspECENS, A COMPROMISE OF THE GFS, ECMWF AND UKMET SHOULD STILL &nbspSUFFICE, AND THIS CONSENSUS IS GENERALLY SUPPORTED BY THE LATEST &nbspCMC AS WELL. &nbsp &nbsp&nbsp &nbsp..SHORTWAVES CROSSING THE GREAT BASIN, MIDWEST AND GREAT LAKES &nbsp&nbsp &nbsp..STRONGER ENERGY OVER THE PACIFIC NORTHWEST BY SATURDAY &nbsp &nbsp~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ &nbspPREFERENCE: BLEND OF THE 12Z GFS/12Z UKMET AND 12Z ECMWF &nbspCONFIDENCE: SLIGHTLY ABOVE AVERAGE &nbsp &nbspMULTIPLE NORTHERN STREAM SHORTWAVES ARE EXPECTED TO TRAVERSE THE &nbspNORTHERN U.S. OVER THE NEXT FEW DAYS. THE MODELS SHOW GOOD &nbspAGREEMENT WITH THE FIRST SHORTWAVE THAT CROSSES A PORTION OF THE &nbspNORTHWEST TODAY AND THEN QUICKLY EJECTS EAST ACROSS THE PLAINS AND &nbspMIDWEST THROUGH THURSDAY. THIS ENERGY THEN CROSSES THROUGH THE &nbspNORTHEAST BY FRIDAY. THEN A SECOND SHORTWAVE TRAVERSES THE &nbspNORTHWEST ON FRIDAY AND EJECTS OUT ACROSS THE MIDWEST ON SATURDAY. &nbspTHE MODELS ARE IN GOOD AGREEMENT WITH THIS SECOND SHORTWAVE MINUS &nbspTHE 12Z NAM WHICH IS A SOMEWHAT SLOWER AND MORE AMPLIFIED OUTLIER &nbspBY SATURDAY OVER THE MIDWEST. &nbsp &nbspA THIRD AND STRONGER SHORTWAVE IMPULSE THEN DROPS SOUTH DOWN &nbspCOASTAL AREAS OF BRITISH COLUMBIA ON FRIDAY AND INTO THE PACIFIC &nbspNORTHWEST ON SATURDAY. A WELL-DEFINED LOW CENTER WILL ACCOMPANY &nbspTHIS NEXT SURGE OF ENERGY. THE 12Z NAM IS THE SLOWEST WITH THIS &nbspSYSTEM, WITH THE 12Z UKMET AND 12Z ECMWF THE FASTEST. THE 12Z GFS &nbspAND 12Z CMC SPLIT THE DIFFERENCE WITH TIMING BETWEEN CAMPS. WILL &nbspLEAN OVERALL TOWARD THE MORE PROGRESSIVE CONSENSUS WITH THE IDEA &nbspOF MORE VIGOROUSLY DIGGING ENERGY ARRIVING TOWARD THE PACIFIC &nbspNORTHWEST GIVEN THE STRENGTH OF THE MEAN LAYER RIDGE NOSING UP &nbspACROSS THE GULF OF ALASKA BY SATURDAY. THUS, COLLECTIVELY A BLEND &nbspOF THE GFS, UKMET AND ECMWF WILL BE PREFERRED WITH THE NORTHERN &nbspSTREAM SHORTWAVES. &nbsp &nbsp &nbspPREVIOUS MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML &nbspPREVIOUS 500 MB FORECASTS AT &nbspWWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML &nbsp &nbspORRISON &nbsp &nbsp &nbsp